Flexible pressure vessel for assembled ammunition casing

ABSTRACT

An ammunition case includes an elongate interior cavity for receiving a propellant and a projectile and extending along a longitudinal axis between a top end and a bottom end, and a bottom corner of the cavity having a reversed radius design supported by a shaped base.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit from U.S. Provisional Patent ApplicationSer. No. 62/500,786, filed May 3, 2017, and U.S. Provisional PatentApplication Ser. No. 62/553,578, filed Sep. 1, 2017, both of which areincorporated by reference in their entireties.

STATEMENT REGARDING GOVERNMENT INTEREST

None.

BACKGROUND OF THE INVENTION

The present invention relates to ammunition articles, and moreparticularly to a flexible pressure vessel for an assembled ammunitioncasing.

Firearm ammunition cartridges typically include a casing holding theprojectile or bullet, a propellant, such as gunpowder or cordite, and anigniting means including a primer or igniting medium. Thus, the casingis used as a container for functionally holding together and arrangingthe other cartridge components. In general, because of the extremenature of the application, materials used for fabrication of ammunitioncartridges must demonstrate excellent mechanical properties. Ammunitionfor civilian and military use has been built using single piece brasscasings for one hundred fifty years. Other materials such as aluminumand steel have also been used in efforts to reduce price or hasalternate supply when the copper supply becomes tight. However, verylittle effort has gone into casing improvement over the years.

It has been desirable in the cartridge design to improve the pressurewithstanding capability of the casing. Recent developments in two piececasings have brought promise. A casing is already marketed having astainless pressure vessel mated to an aluminum alloy base. However, oneof the limiting factors is increased pressure is the ability of thebottom corner of the pressure vessel to withstand the desired higherpressures. The lower corner of the tube is the weakest part of thedesign.

What is needed is an improvement apparatus to overcome these and othershortcomings.

SUMMARY OF THE INVENTION

The following presents a simplified summary of the innovation in orderto provide a basic understanding of some aspects of the invention. Thissummary is not an extensive overview of the invention. It is intended toneither identify key or critical elements of the invention nor delineatethe scope of the invention. Its sole purpose is to present some conceptsof the invention in a simplified form as a prelude to the more detaileddescription that is presented later.

In general, in one aspect, the invention features an ammunition caseincluding an elongate interior cavity for receiving a propellant and aprojectile and extending along a longitudinal axis between a top end anda bottom end, and a bottom corner of the cavity having a reversed radiusdesign supported by a shaped base.

In another aspect, the invention features an ammunition case includingan elongate interior cavity for receiving a propellant and a projectileand extending along a longitudinal axis between a top end and a bottomend, and a bottom corner of the cavity having a broad radius designsupported by a shaped base.

In still another aspect, the invention features an ammunition caseincluding an elongate interior cavity for receiving a propellant and aprojectile and extending along a longitudinal axis between a top end anda bottom end, and a bottom corner of the cavity having an angle/radiuscombination supported by a shaped base.

In another aspect, the invention features an ammunition case including acase, the case having a wall deformed in a pattern of deformationsdirected inwardly, enabling a balance of outer profile maintenance forgeneral loading and handling while giving spring characteristics of inan axial direction.

In another aspect, the invention features an ammunition case includingan elongate interior cavity for receiving a propellant and a projectileand extending along a longitudinal axis between a top end and a bottomend, and having one or more grooves rolled into the sidewall above abottom corner.

These and other features and advantages will be apparent from a readingof the following detailed description and a review of the associateddrawings. It is to be understood that both the foregoing generaldescription and the following detailed description are explanatory onlyand are not restrictive of aspects as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood with reference to the followingdescription, appended claims, and accompanying drawings where:

FIGS. 1A and 1B show cross sectional views of prior art cartridgescasings for firearm ammunition.

FIG. 2 is a cross-sectional view of a first embodiment of an exemplaryammunition case.

FIG. 3 is a cross-sectional view of a second embodiment of an exemplaryammunition case.

FIG. 4 is a cross-sectional view of a third embodiment of an exemplaryammunition case.

FIG. 7 is a cross-sectional view of a fourth embodiment of an exemplaryammunition case.

FIG. 6 is a cross-sectional view of a fifth embodiment of an exemplaryammunition case.

FIG. 7 is a cross-sectional view of a sixth embodiment of an exemplaryammunition case.

DETAILED DESCRIPTION

The subject innovation is now described with reference to the drawings,wherein like reference numerals are used to refer to like elementsthroughout. In the following description, for purposes of explanation,numerous specific details are set forth in order to provide a thoroughunderstanding of the present invention. It may be evident, however, thatthe present invention may be practiced without these specific details.In other instances, well-known structures and devices are shown in blockdiagram form in order to facilitate describing the present invention.

As shown in FIG. 1A, an exemplary prior art cartridge casing 1 iselongate and is constituted by a plate shaped bottom wall and a sidewall3 extending upwardly generally perpendicularly from the bottom wall 2.Thus, the casing 1 is hollow and defines an elongate interior cavity 4.The bottom wall 2 has a circular shape, and, accordingly, the sidewall 3has cylindrical symmetry about a longitudinal axis 5 of the casing 1 andthe cavity 4.

The sidewall 3, which is an elongate tubular portion, includes inlongitudinal direction sections 6 a and 6 b having different diametersand a corresponding transition region 6 c between the lower, largerdiameter section 6 b and the upper, smaller diameter section 6 a. Thesections 6 a and 6 b may or may not be slightly tapered in thelongitudinal direction, in particular in a direction away from thebottom wall 2.

The bottom wall 2 includes a through bore 7 which extends in alongitudinal direction and has a lower, large diameter section 7 aextending from a lower axial end surface 8 of the bottom wall 2 and anupper, small diameter section 7 b.

The casing 1 is composed of two separate elements or components, namelyan elongate tubular sleeve component 10 and a bottom component 11, whichare mechanically secured to each other. The sleeve component 10 is notidentical with the elongate tubular portion forming the sidewall 3, butthat the sleeve component 10 also forms a relatively small portion ofthe bottom wall 2. Consequently, while the bottom component 11 formsnearly all of the bottom wall 2, it does not form the entire bottom wall2.

The material from which the sleeve component 10 is constructed is of aconsiderably lower thickness than the material from which the bottomcomponent 11 is constructed. Thus, the thickness of the sleeve component10 throughout its entire extension is smaller than the thickness of theentire bottom component 11, with the exception of a portion 16. Inparticular, the thickness contribution provided by the bottom component11 to the total thickness of the bottom wall 2 in the longitudinaldirection is considerably larger than the material thickness anywhere inthe sleeve component 10.

For allowing a simple mechanical attachment of the bottom component 11to the sleeve component 10, the sleeve component 10 is formed such thatat its lower end 12 it includes a radially inwardly projecting annularflange 13, the lower surface 14 of which constitutes an annular loweraxial end surface or bottom surface of the sleeve component 10. Thesurface 14 is the lowermost portion of the sleeve component 10, i.e. thelower terminal axial end thereof. This bottom surface 14 of the sleevecomponent 10 is arranged in abutment with a corresponding annular upperaxial end surface 15 of the bottom component 11 and may be attachedthereto by suitable means.

The attachment is effected by the annular bent-back portion 16 of thebottom component 11, which extends in parallel to and at a certain axialdistance from the annular upper axial end surface 15 of the bottomcomponent 11 in the immediate vicinity of the through bore 7. Theannular flange 13 of the sleeve component 10 is arranged to extend intothe annular space defined by the end surface 15 and the bent-backportion 16 of the bottom component 11, and the sleeve component 10 isthereby locked in place and securely retained on the bottom component 11in the position illustrated. Due to the mating construction of theannular bent-back portion 16 of the bottom component 11 and of theannular flange 13 of the sleeve component 10, the sleeve component 10and the bottom component 11 are self-centering upon assembly.

The bottom component 11 has the shape of a planar ring. In thelongitudinal direction it includes two adjacent sections 17 a, 17 bhaving different diameters and forming a sharp rectangular step 19between them. Thus, the bottom component 11 includes a lowermost annularprojection 18 radially outwardly projecting as compared to the recessedportion 17 b and actually the entire remainder of the bottom component11. A lower end 12 of the sleeve component 10 and, consequently, theperipheral outer edge 20 of the annular flange 13 of the sleevecomponent 10 has a diameter which is larger than the diameter of therecessed portion 17 b of the bottom component 11 and is identical orsubstantially identical to the diameter of the annular projection 18 ofthe bottom component 11. Due to this construction, an annular groove 21is present in the radial outer surface of the bottom component 11,wherein the borders or sidewalls of this groove 21 are formed by the twosteps 19 and 20. In the assembled cartridge the groove 21 serves as theextractor groove for extracting the empty casing 1 from the firingchamber of the firearm following actuation thereof.

It is also possible for the section 17 b to have the same or essentiallythe same radial diameter than the or a lower end 12 of the sleevecomponent 10 and, consequently, the peripheral outer edge 20 of theannular flange 13 of the sleeve component 10. In such a case, thecartridge casing 1 does not include an extractor groove, but the annularprojection 18 at the very bottom of the bottom component 11 and the stepbetween the projection 18 and the recessed portion 17 b is provided forengagement by an extraction mechanism.

As can be seen in FIG. 1B, another prior art ammunition case 100includes a sharp corner 102 and is an area of stress concentration. Highstress is created during firing as the case sidewall 104 is held to thebreach by friction and the bottom is acted on by internal case pressure.The sharp corner 102 is an area where the motion of the sidewallradially to the breach wall is discontinuous from the motion of thebottom axially away from the interior of the case. The compression ofthe aluminum base allows enough motion for the corner to fail at highcase pressure. More specifically, it is a combination of the compressionof the base and the breach head space along with the friction tractionon the sidewall that require that the case sidewall be able to stretchto conform to the breach interior volume. Head space is the breachcavity design allowance that exceeds the loaded cartridge length andallows the cartridge to fit loosely in length into the closed breachcavity.

The problem is made worse by a design that requires an internal cornerradius of less than the material thickness. Forming this radiusnecessarily reduces the cross sectional thickness in the are of theradius further reducing the load carrying capability. Thus, the sharpcorner 102 is the area where the motion of the sidewall radially to thebreach wall is discontinuous from the motion of the bottom axially awayfrom the interior of the case.

As shown in FIG. 2, a first embodiment of an ammunition case 200 of thepresent invention includes a bottom corner 202 of a cavity 204 having areversed radius design supported by the shaped base. The support of thealuminum base prevents failure at high case pressure.

As shown in FIG. 3, a second embodiment of an ammunition case 300 of thepresent invention includes a bottom corner 302 of the cavity 304 havinga broad radius 306 supported by the shaped base. Here again, support ofthis aluminum base prevents failure at high case pressure.

As shown in FIG. 4, a third embodiment of an ammunition case 400 of thepresent invention includes a bottom corner 402 of a cavity 404 having anangle/radius combination 406 supported by the shaped base. With thisdesign, support of this aluminum base prevents failure at high casepressure.

Other embodiments of the present invention further enable an ability ofa bottom corner of a pressure vessel to withstand high pressures. InFIG. 5, an ammunition case 500 exhibits a geometry in a case 502 wallthat enables axial expansion of the case wall 502 so that it can travelwith a base 504 during a high pressure event to where it is ultimatelystill supported by the base 504 at full travel. To accomplish this, theexterior of the case wall 502 is deliberately deformed in a lower areaduring manufacturing to construct a spring wall section 506. The springwall section 506 has curvilinear path to the barrel wall and extends totravel with the compressed base 504 without exceeding a tensile or shearload of the case wall 502 at or near a corner.

Various geometries of “spring” can be built into the casing 502 to tuneit to a desired performance. The enables manufacture of thin wall and/orlight weight casings to use thinner and/or lower strength materials.While prior designs have used austenitic stainless, the wall springdesign of the present invention enables a use of a larger variety oflower strength material. Our design also enables thinner materials to beused to lower stress at a weak point.

In FIG. 6, an ammunition case 600 includes deformation of a case wall602 made in a pattern 604 of deformations (i.e., dimples of varyinggeometries) directed inwardly. This design enables a balance of outerprofile maintenance for general loading and handling while giving springcharacteristics of the structure in an axial direction. During firing,internal pressure forces the case wall 602 against a supporting barreland the tube is stretched in an axial direction allowing a bottom 606 ofthe case wall 602 to be supported by the bottom 606.

In FIG. 7, an ammunition case 700 includes deformation of a case wall702 made in a pattern 704 of deformations (i.e., single row of dimples)directed inwardly.

Other embodiments may be included. For example, in one embodiment, analuminum alloy base is replaced by a base of higher modulus ofelasticity. The higher modulus material will not deform as much under afiring pressure and this prevent a tube from deforming to a limit offailure. Other material can include stainless steel and other ironalloys having both low cost and easy manufacturing. While an iron alloybase may weigh more than an aluminum alloy base and detracts from anoverall weight reduction goal, a final assembly will still weigh lessthan existing brass ammunition cases. In higher length to diameter ratiodesigns like rifle casing, the effect of base weight is diminished.

In another embodiment, a typical ammunition case material is reduced upto 50% in thickness. In this design for current gun barrels designed toaccept bullets and cartridges of defined dimensions, it is stillnecessary for an open end (bullet end) of the case to maintain bothbarrel fit on the outside diameter and bullet fit and retention on aninside diameter. To accomplish this, a compression ring is added to aneck of the tube such that the effective thickness of the assembled neckis returned to the design standard.

In still another embodiment, a casing can be designed to optimum weighperformance and simplicity of manufacture by requiring a new gun barrelbreach configuration that accepts a reduced thickness casing. Here thecasing, reduced up to 50% in thickness, does not need an additionalcompression collar on a neck.

In certain applications, it is desirable to have an ammunition casingthat cannot be easily reused. A geometry of deformation can be createdsuch that a deformation under firing is plastic and the casing does notreturn to its original shape, making the case more difficult orimpossible to reload.

It would be appreciated by those skilled in the art that various changesand modifications can be made to the illustrated embodiments withoutdeparting from the spirit of the present invention. All suchmodifications and changes are intended to be within the scope of thepresent invention except as limited by the scope of the appended claims.

What is claimed is:
 1. An ammunition case comprising: an elongateinterior cavity for receiving a propellant and a projectile andextending along a longitudinal axis between a top end and a bottom end;and a bottom corner of the cavity having a reversed radius designsupported by a shaped base.
 2. The ammunition case of claim 1 wherein acasing encloses the elongate interior cavity, an exterior of the casingdeformed in a lower area during manufacturing to exhibit a spring wallsection.
 3. The ammunition case of claim 1 wherein a casing encloses theelongate interior cavity, an exterior of the casing having a pattern ofdeformations directed inwardly.
 4. The ammunition case of claim 3wherein the pattern of deformations are dimples of varying geometries.5. The ammunition case of claim 3 wherein the pattern of deformationsare a single row of dimples.
 6. An ammunition case comprising: anelongate interior cavity for receiving a propellant and a projectile andextending along a longitudinal axis between a top end and a bottom end;and a bottom corner of the cavity having a broad radius design supportedby a shaped base.
 7. The ammunition case of claim 6 wherein a casingencloses the elongate interior cavity, an exterior of the casingdeformed in a lower area during manufacturing to exhibit a spring wallsection.
 8. The ammunition case of claim 6 wherein a casing encloses theelongate interior cavity, an exterior of the casing having a pattern ofdeformations directed inwardly.
 9. The ammunition case of claim 8wherein the pattern of deformations are dimples of varying geometries.10. The ammunition case of claim 8 wherein the pattern of deformationsare a single row of dimples.
 11. The ammunition case of claim 8 whereinthe pattern of deformations are one or more circumferential rings. 12.An ammunition case comprising: an elongate interior cavity for receivinga propellant and a projectile and extending along a longitudinal axisbetween a top end and a bottom end; and a bottom corner of the cavityhaving an angle/radius combination supported by a shaped base.
 13. Anammunition case comprises: a case, the case having a wall deformed in apattern of deformations directed inwardly, enabling a balance of outerprofile maintenance for general loading and handling while giving springcharacteristics of in an axial direction.
 14. The ammunition case ofclaim 13 wherein the pattern of deformations comprises grooves ordimples of varying geometries.
 15. An ammunition case comprising: anelongate interior cavity for receiving a propellant and a projectile andextending along a longitudinal axis between a top end and a bottom end;and having one or more grooves rolled into the sidewall above a bottomcorner.